Ultra high entropy material-based non-reversible spectral signature generation via quantum dots

Abstract

A physically unclonable function (PUF) device is provided, comprising an excitation source providing light for exciting quantum dots (QDs); a first layer of a material having contained therein a first random distribution of first QDs of a first type that are configured to generate a first color in response to being excited by the excitation source; a second layer of a second material having contained therein a second random distribution of second QDs of a second type that are configured to generate a second color, different from the first color, in response to being excited by the first excitation source, and a detector fixedly attached to one of the first and second layers and configured for detecting a pattern of light emitted by at least one of the first QDs and the second QDs and for providing an output indicative of the detected pattern.

What is claimed is: 
     
       1. A method of making a physically unclonable function (PUF) device, the method comprising:
 (a) forming a layered structure by:
 (a-1) providing a first layer of a first optically clear medium; 
 (a-2) infusing a first random distribution of first quantum dots (QDs) of a first type, disposed at a first plurality of random locations, into the first layer wherein the first type of QDs are configured to generate a first color in response to being excited by an excitation source; 
 (a-3) partially curing the first layer such that at least a first portion of the first random distribution of first QDs are fixed into at least a first portion of the first plurality of random locations and such that at least a second portion of the first random distribution of first QDs are not in a fixed position; 
 (a-4) applying a second layer of a second optically clear medium, over the first layer of optically clear medium, after partially curing the first layer of optically clear medium; 
 (a-5) infusing a second random distribution of second quantum dots (QDs) of a second type, disposed at a second plurality of random locations, into the second layer of optically clear medium, wherein the second type of QDs are configured to generate a second color in response to being excited by the excitation source, wherein the second color is different than the first color, wherein the infusion of the second random distribution of second QDs is configured so that at least a third portion of the second random distribution of second QDs are intermingled with the second portion of the first random distribution of first QDs; and 
 (a-6) curing the second layer of optically clear medium to a degree sufficient to ensure that both the first random distribution of first QDs and the second random distribution of second QDs are substantially fixed into position; and 
 
 (b) operably coupling a detector and an excitation source to the layered structure so that the excitation source is configured to direct light to the first layer of optically clear medium and to the second layer of optically clear medium and so that the detector is configured to detect a pattern of light that arises from directing light at the first random distribution of first QDs and at the second random distribution of second QDs; and 
 (c) constructing and arranging the excitation source, first layer of optically clear medium, second layer of optically clear medium, and detector so that the light and the pattern of light are externally unrevealed. 
 
     
     
       2. The method of  claim 1 , further comprising:
 (g) constructing and arranging the layered structure, detector and source so that the pattern of light has a first appearance if the detector is operably coupled to the first layer of optically clear medium and a second appearance if the detector is operably coupled to the second layer of optically clear medium, wherein the first and second appearance are different. 
 
     
     
       3. The method of  claim 1 , wherein the first random distribution of first QDs are associated with a first bandgap and the second random distribution of second QDs are associated with a second bandgap that is different than the first bandgap, wherein partially curing the first layer of optically clear medium is configured to ensure that the first layer of optically clear medium and the second layer of optically clear medium form a quasi-heterogenous layering of different bandgap QDs. 
     
     
       4. The method of  claim 1 , further comprising:
 (a-7) operably coupling the layered structure to a support structure. 
 
     
     
       5. The method of  claim 1 , wherein the layered structure is formed directly onto a support structure. 
     
     
       6. The method of  claim 5 , wherein the support structure comprises a three-dimensional object. 
     
     
       7. The method of  claim 1 , further comprising:
 (a-7) applying a reflector to the second layer of optically clear medium, after curing the second layer of optically clear medium. 
 
     
     
       8. The method of  claim 7 , wherein the reflector is configured to re-direct unabsorbed light back into the layered structure. 
     
     
       9. The method of  claim 7 , wherein the reflector is configured to provide at least one of mechanical and electrical protection for the layered structure. 
     
     
       10. The method of  claim 7 , wherein the reflector is configured to help conceal the pattern of light that arises from directing light at the first random distribution of first QDs and at the second random distribution of second QDs, to help ensure that at least one of the light and the pattern of light are externally unrevealed. 
     
     
       11. The method of  claim 1 , further comprising enclosing at least a portion of the PUF device within a tamper evident structure, wherein an arrangement of the PUF device and the tamper evident structure is configured so that an attempt to view the layered structure will cause a damage to at least one of the first random distribution of first QDs and the second random distribution of second QDs, wherein the damage changes the pattern of light. 
     
     
       12. The method of  claim 1 , further comprising:
 (c) operably coupling an external control signal to the excitation source, wherein the external control signal is configured to control the light that the excitation source directs to the first layer of optically clear medium and to the second layer of optically clear medium. 
 
     
     
       13. The method of  claim 1 , further comprising:
 (c) operably coupling a computer system to the layered structure, the computer system configured to interpret the pattern of light detected by the detector. 
 
     
     
       14. The method of  claim 1 , wherein step (a-6) further comprises:
 (a-6-1) partially curing the second layer of optically clear medium such that at least a first portion of the second random distribution of second QDs are fixed into at least a first portion of the second plurality of random locations and such that at least a second portion of the second random distribution of second QDs are not in a fixed position; 
 (a-6-2) applying a third layer of a third optically clear medium, over the second layer of optically clear medium, after partially curing the second layer of optically clear medium; 
 (a-6-3) infusing a third random distribution of third QDs of a third type, disposed at a third plurality of random locations, into the third layer of optically clear medium, wherein the third type of QDs are configured to generate a third color in response to being excited by the excitation source, wherein the third color is different than the first color and is different than the second color, wherein the infusion of the third random distribution of third QDs is configured so that at least a fourth portion of the third random distribution of third QDs are intermingled with the second portion of the second QDs; and 
 (a-6-4) curing the first layer of optically clear medium, second layer of optically clear medium, and third layer of optically clear medium to a degree sufficient to ensure that the first random distribution of first QDs, second random distribution of second QDs, and third random distribution of third QDs, are substantially fixed into position; 
 wherein the excitation source is configured to direct light to the first layer of optically clear medium, second layer of optically clear medium and third layer of optically clear medium, and wherein the detector is configured to detect a pattern of light that arises from directing light at the first random distribution of first QDs, second random distribution of second QDs, and third random distribution of third QDs; and 
 wherein the excitation source, first layer of optically clear medium, second layer of optically clear medium, and third layer of optically clear medium, are constructed and arranged so that the light and the pattern of light are externally unrevealed. 
 
     
     
       15. The method of  claim 14 , wherein the layered structure, detector and excitation source are constructed and arranged so that the pattern of light has a first appearance if the detector is fixedly attached to the first layer of optically clear medium and a second appearance if the detector is fixedly attached to the third layer of optically clear medium, wherein the first and second appearance are different. 
     
     
       16. The method of  claim 14 , wherein the first, second, and third layers are constructed and arranged so that the first color of light associated with the first random distribution of first QDs has a shorter wavelength of light than the second color of light associated with the second random distribution of second QDs and wherein the second color of light associated with the second random distribution of second QDs has a shorter wavelength of light than the third color of light associated with the third random distribution of third QDs. 
     
     
       17. A method of making a physically unclonable function (PUF) structure, the method comprising:
 providing a first layer of a first optically clear medium; 
 infusing a first random distribution of first quantum dots (QDs) of a first type, disposed at a first plurality of random locations, into the first layer of first optically clear medium, wherein the first type of QDs are configured to generate a first color in response to being excited by an excitation source; 
 partially curing the first layer of first optically clear medium such that at least a first portion of the first random distribution of first QDs are fixed into at least a first portion of the first plurality of random locations and such that at least a second portion of the first random distribution of first QDs are not in a fixed position; 
 applying a second layer of a second optically clear medium, over the first layer of first optically clear medium, after the partially curing of the first layer of first optically clear medium; 
 infusing a second random distribution of second quantum dots (QDs) of a second type, disposed at a second plurality of random locations, into the second layer of second optically clear medium, wherein the second type of QDs are configured to generate a second color in response to being excited by the excitation source, wherein the second color is different than the first color, wherein the infusion of the second random distribution of second QDs is configured so that at least a third portion of the second random distribution of second QDs are intermingled with the second portion of the first random distribution of first QDs; and 
 curing the first layer of first optically clear medium and the second layer of second optically clear medium to a degree sufficient to ensure that both the first random distribution of first QDs and the second random distribution of second QDs are substantially fixed into position and so that the first layer of first optically clear medium and the second layer of second optically clear medium, form a layered structure having a first side adjacent to the first layer of first optically clear medium and a second side adjacent to the second layer of second optically clear medium; 
 wherein the layered structure is configured so that, when a detector is operably coupled to the second side of the layered structure and when an excitation source is coupled to the first side of the layered structure, the excitation source is configured to direct light through the first layer of first optically clear medium and through the second layer of second optically clear medium, and the detector is configured to detect a first pattern of light that arises from directing light at the first random distribution of first QDs and the second random distribution of second QDs; and 
 wherein the layered structure is configured so that, when the layered structure is operably coupled to the excitation source and detector, the light that is directed and the first pattern of light that arises, are externally unrevealed. 
 
     
     
       18. The method of  claim 17 , wherein the PUF structure is configured so that, when a detector is operably coupled to the first side of the PUF structure and when an excitation source is coupled to the second side of the PUF structure, the excitation source is configured to direct light through the second layer of second optically clear medium and through the first layer of first optically clear medium, and the detector is configured to detect a second pattern of light that arises from directing light at the second random distribution of second QDs and at the first random distribution of first QDs, wherein the second pattern of light is different than the first pattern of light. 
     
     
       19. A method of making a physically unclonable function (PUF) device, the method comprising:
 providing an article of manufacture having at least one surface thereon; 
 coupling a detector to the at least one surface; 
 encapsulating the article of manufacture, including the detector, in a layer of optically clear medium; 
 infusing a random distribution of quantum dots (QDs) of a plurality of different bandgap types, disposed at a plurality of random locations, into the layer of optically clear medium, wherein the plurality of different bandgap types of the random distribution of QDs, are configured to generate a corresponding plurality of different colors in response to being excited by an excitation source; 
 embedding at least one detector within the optically clear medium; 
 curing the layer of optically clear medium to a degree sufficient to ensure that the random distribution of QDs and the detector, are substantially fixed into position; and 
 configuring the article of manufacture so that when the excitation source is configured to direct light through the layer of optically clear medium, the detector is configured to detect a pattern of light that arises from light impinging on the random distribution of QDs; and 
 wherein the article of manufacture, the layer of optically clear material, the random distribution of QDs, and the excitation source, are configured so that, when the excitation source directs light through the layer of optically clear material, the light that is directed and the pattern of light that arises, are externally unrevealed. 
 
     
     
       20. The method of  claim 19 , further comprising:
 operably coupling an external system to the detector, the external system configured to interpret the pattern of light detected by the detector.